It is known how artificial joints, such as knee, hip, heel and elbow joints often have to be removed for various reasons and mainly following local infections after a surgical implant.
In such a case, it is not possible to replace immediately the unsuccessful prosthesis with a new one, but the seat of the joint must be treated with suitable antibiotics before a new surgical operation can be performed.
In the meantime, the space within the joint must be maintained in order to prevent a reduction in the articular space, retraction of the tissues, atrophying of the joint and loss of muscular elasticity and tone.
Spacing devices used in the two-stage implant of artificial joints, for treatment of both the hip and the knee, are known.
Italian patent application No. VR95A000072 describes a disposable spacing device for an artificial hip joint, essentially characterized in that it is made of a biocompatible base material of the type used for bone cements.
Spacing devices for knee joints which are manually made by the surgeon at the time of the surgical operation are also known, these devices being made from blocks of bone cement of standard shape, optionally containing active constituents.
A drawback of these known methods of treatment is that they do not allow the space within the joint to be kept apart in an ergonomically and anatomically correct manner. Moreover, the long time required for preparation increases the difficulties for the surgeon and reduces the probability of success of the operation.
In order to overcome these drawbacks, spacing devices have been made using suitable anatomically and ergonomically shaped moulds which are filled with bone cement in situ. However, these known spacing devices do not allow mobilisation of the joint and result in the need for a long rehabilitation after reimplanting the permanent prosthesis.
In still other cases, the spacing devices have been obtained by lining a permanent metal prosthesis with bone cement. Although this solution allows a temporary articulation, it is difficult to prepare and in spite of use of cement-lined prostheses requires that such devices are positioned in infected seats, which most of the surgeon consider a worsening infection factor.